Psoriasis

People who get psoriasis usually have one or more person in their family who has psoriasis. Not everyone who has a family member with psoriasis will get psoriasis.

What causes psoriasis?

Psoriasis is not contagious.You cannot get psoriasis from touching someone who has psoriasis.You cannot get psoriasis from swimming in the same pool or having sex.

Scientists have learned that a person’s immune system and genes play important roles. It seems that many genes must interact to cause psoriasis.

Scientists also know that not everyone who inherits the genes for psoriasis will get psoriasis. It seems that a person must inherit the “right” mix of genes. Then the person must be exposed to a trigger.

Many people say that their psoriasis began after they experienced one of these common psoriasis triggers:

A stressful event

Strep throat

Taking certain medicines, such as lithium or medicine to prevent malaria

Cold, dry weather

A cut, scratch or bad sunburn.

Plaque psoriasis

Raised reddish patches on the skin called plaque (plak)

Patches may be covered with a silvery-white coating, which dermatologists call scale

Patches can appear anywhere on the skin

Most patches appear on the knees, elbows, lower back, and scalp

Patches can itch

Scratching the itchy patches often causes the patches to thicken

Patches vary in size and can appear as separate patches or join together to cover a large area

Nail problems — pits in the nails, crumbling nail, nail falls off

Guttate psoriasis

Small, red spots (usually on the trunk, arms, and legs but can appear on the scalp, face, and ears).